Core drilling for exploration purposes are usually preformed with rock drilling rigs where drill string components are positioned in the active drill string position, are lifted up and lowered down into the drill hole with the aid of a winch. The winch wire is attached to the uppermost drill string component with the aid of a lifting plug. Since core drilling aims at collecting a drilled-out core of rock to be investigated, it is the question about tubular drill string components. When the drill string is lifted up, which occurs frequently in order to exchange drill bits, the tubular string is lifted up unit by unit, whereby the single pipes are separated from each other with the aid of the rotator device of the rock drilling rig in co-operation with a lower pipe holder.
Final loosening of a pipe to be taken away from the tubular string is at present preformed by hand by the operators, wherein this handling includes final screwing apart, lifting and guiding of the pipe to the area of a pipe magazine.
During lowering of the drill string, the work operations are reversed so that new drill string components in the form of pipes are successively lifted to a position where they are aligned with the drill string and threaded together by the operator. These work operations are straining for the operator and results in a risk of lift and crash injuries to the operator that cannot be neglected.
Core drilling is often preformed to great depths, such as for example with drill lengths between one and two kilometers. Because of the wear that the drill bit is subjected to, it has to be exchanged relatively often, which results in that the entire drill string has to be picked up from the drill hole, be mounted apart into drill string components, the worn drill bit be taken away and be replaced with a new one, whereupon the drill string can again be lowered down into the hole. Thereupon a further distance is drilled until the drill bit has to be exchanged again etc. During the drilling, a flush water swivel is connected to the upper end of the drill string for providing flushing fluid for transporting away drill cuttings that have been removed through drilling.